Successful inclusion is dependent upon teachers implementing classroom adaptations. Teacher beliefs can be expected to play a key role in their decision to make such adaptations. Using a cross-sectional survey, the purpose of the study was to examine mainstream school teachers' explicit and implicit attitudes, self-efficacy and intentions towards children with intellectual disability and to assess their relationship to inclusive teaching. Primary school teachers working in Scotland were invited to take part. Eighty-seven participants completed a questionnaire measuring explicit attitudes, self-efficacy, intentions and inclusive teaching. Participants also completed a Single-Target Implicit Association Test assessing implicit attitudes. The results indicated that self-efficacy predicted reported inclusive behaviour and mediated the relationship between explicit attitudes and reported behaviour. Implicit attitudes did not relate to explicit beliefs (attitudes, self-efficacy, intentions) or behaviour.